/**
 * Copyright (C) 2006 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.ivcode.guice.asynchronous.internal.proxy;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import net.sf.cglib.proxy.MethodProxy;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

/**
 * Intercepts a method with a stack of interceptors.
 * 
 * @author crazybob@google.com (Bob Lee)
 */
public final class InterceptorStackCallback implements net.sf.cglib.proxy.MethodInterceptor {

    final MethodInterceptor[] interceptors;
    final Method method;

    public InterceptorStackCallback(Method method, List<MethodInterceptor> interceptors) {
        this.method = method;
        this.interceptors = interceptors.toArray(new MethodInterceptor[interceptors.size()]);
    }

    public Object intercept(Object proxy, Method method, Object[] arguments, MethodProxy methodProxy) throws Throwable {
        return new InterceptedMethodInvocation(proxy, methodProxy, arguments).proceed();
    }

    @Override
	public String toString() {
		return "InterceptorStackCallback [interceptors="
				+ Arrays.toString(interceptors) + ", method=" + method + "]";
	}

	private class InterceptedMethodInvocation implements MethodInvocation {

        final Object proxy;
        final Object[] arguments;
        final MethodProxy methodProxy;
        int index = -1;

        private InterceptedMethodInvocation(Object proxy, MethodProxy methodProxy, Object[] arguments) {
            this.proxy = proxy;
            this.methodProxy = methodProxy;
            this.arguments = arguments;
        }

        public Object proceed() throws Throwable {
            try {
                index++;
                return index == interceptors.length ? methodProxy.invokeSuper(proxy, arguments) : interceptors[index].invoke(this);
            } finally {
                index--;
            }
        }

        public Method getMethod() {
            return method;
        }

        public Object[] getArguments() {
            return arguments;
        }

        public Object getThis() {
            return proxy;
        }

        public AccessibleObject getStaticPart() {
            return getMethod();
        }

		@Override
		public String toString() {
			return "InterceptedMethodInvocation [proxy=" + proxy
					+ ", arguments=" + Arrays.toString(arguments)
					+ ", methodProxy=" + methodProxy + ", index=" + index + "]";
		}
    }
}
